Dam Alteration Identification by Extended Full-Waveform Inversion and Multiphase XFEM

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Dams are important structures employed in the generation of hydro-electricity, provision ofwater supply and for flood defense. However, a large percentage of dams in operation today are more than 50 years old and as such the true condition of its structural integrity is not fully known.The deterioration of dams may result both from short term effects (e.g earthquakes, impact loads, etc) and from long term effects (e.g. aging, physical and chemical weathering, fatigue etc). Though these effects may not lead to an immediate collapse/failure of the dam, it is necessary, in order to ensure optimum performance of these structures, to identify quickly regions which may jeopardize the safety of the dam. Unfortunately the conventional methods are tedious, time consuming, expensive and inefficient.The method proposed in this project draws inspiration from the recorded success of full-waveform inversion (FWI) application in subsurface exploration and for non-destructive testing (NDT) in geotechnical engineering. Here not only do we intend exploiting the advantages of FWI in providing precise and reliable results but also the adaptation and extension of the method for damage identification in structures with dominant multiphase-multifield effects. In order to increasethe robustness and reliability of the proposed method, all the necessary phenomena surrounding the operation of the structure will be incorporated. Additionally, the stability (robustness) and the flexibility of the identification results will be increased be developing and applying a novel two-stage approach which consists of a combination of an extended Finite Element (XFEM)-based inversion and a subsequent FWI. The approach is general and may be applied even to other inverse seismic tomography problems. The proposed technique also takes advantage of recent advancements in computing technology, works in damage identification using XFEM, FWI, FEM-BEM hybridmethods and the optimal design of experiments (DoE). The goal is to efficiently and reliably detect anomalies in dams in a non-destructive manner and to minimize the sophistication and cost incurred by the application of full-waveform inversion (FWI) and conventional structural health monitoring techniques in dams.